A model for Evaporation and Drainage investigations at Ground of Ordinary Rainfed-areas

Once the estimated and measured data from the experiment had been compared for validation, simulations were carried out continuously for the period of 1994-2006 in a semi-arid environment of Turkey. Ep rates were lower during the winter season because of the lesser evaporative demand of the atmosphere. However, Ea rates were mainly found to be functions of the rainfall pattern, and presumably soil wetness in addition to atmospheric evaporative demand. D volumes below 120 cm soil depth were high during rainy months, with a peak in January. Annual Ep varied between 850.6 and 909.8 mm during the period of 13 years. Ea ranged from 248.0 to 392.9 mm with a mean annual value of 302.5 mm. D substantially varied inter-annually (150.5-757.4 mm) depending on the intensity and frequency of rainfall events and especially antecedent soil wetness. The next logical step in model development would be the inclusion of runoff for sloping lands.